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W. N.'NIOHOLSON & A. T. ALLGOGK.

SAFETY VALVE. No.310,459. Patented Jan. 6, 1885.

UNITED STATES PATENT OFFICE.

V. NEYVZAM NICHOLSON AND ARTHUR THOMAS ALLOOOK, OF N EWABK- UPON-TBENT, COUNTY OF NOTTINGHAM, ENGLAND.

SAFETY-VALVE.

SPECIFICATION forming part of Letters Patent No. 310,459, dated January 6, 1885. Application filed November 6,1884. (No model.) Patented in England March 1,1884, No. 4,211.

To all whom it may concern Be it known that we, WILLIAM NEWZAM NICHOLSON and ARTHUR THOMAS ALLoocK, subjects of the Queen of Great Britain, residing at Newark-upo11-Trent, in the county of Nottingham, England, engineers, {have invented certain new and useful Improvements in Safety-Valves, (for which we have obtained a patent in Great Britain, No. 4,211, bearing date March 1, 1884,) of which the following is a specification.

This invention relates to improvements in safety-valves; and it consists in the combination of devices hereinafter described and claimed.

In the appended sheet of drawings, Figure 1 is a side elevation of the valve detached from its seat. Fig. 2 is a longitudinal section, and Fig. Sis a plan of the underside of a complete safety'valve made in accordance with our invention.

It consists of a compound valve made up of the annular valve A, opening outward from its seat a, and an internal central valve, B, closing the annulus and opening inward from its seat I). The inner central valve, B, is provided with a spindle, G, projecting through the annular valve A, and furnished with a loose collar, D, and an adjusting-nut, d, for regulating the pressure of a spiral spring, S, which bears with one extremity against the collar D and with its other end against the annular valve A, so tending to hold the in ternal valve, B, up to its seat 6 on the annular valve A with a force equal to that which is required to hold the whole compound valve down on its seat a against the pressure of the steam in the boiler. The compound valve so formed is weighted down to its seat a by a le ver, L, with a weight or spring, \V, of ordinary construction, which presses on the head of the spindle G of the inner central valve, B. This pressure is transmitted through the spiral spring S to the annular valve A, and so long as it does not exceed that of the spring S the compound valve A and B will act as an ordinary safety-valve. Should, however, the pressure applied by the lever L exceed that of the spring S, the annular valve A will 'be held down to its seat a, the spring S deflected,

and the inner central valve, B, opened inward and the steam allowed to escape.

For the purpose of further calling attention to the escape of steam, due to overweighting the lever L, the dome of a whistle, H, may be attached to the valve-spindle 0, having its edge over the central hole of the annular valve A, so that it may be sounded by the escape of steam "from the valve B, and an audible warning given of the overweighting. Although the drawings show the valve to be weighted by means of the lever L and a weight or spring, W, it is obvious that either of the latter can be applied direct to the valve-spin- (lle 0, without the intermediate lever, L, in in any of the methods in ordinary use. The compound valve A and B and its spring S are inclosed in a case, E, fastened to the baseplate F, and secured by a lock, K, so that the spring S, after having been adjusted to the required pressure, cannot be tampered with. For the purpose of enabling the annular valve A to be rotated on its seat a, one or more stops, N, are formed on or fixed to the bottom of the valve B. They engage with corresponding stops, N, formed on the annular valve A, and which also form guides to direct it on its seat a, By rotating the valvespindle O the stops N come in contact with the stops N on the annular valve A, and so turn it on its seat a, also allowing an interval for the valve B to rotate on its own seat b.

Having now particularly described and ascertained the nature of the said invention and in what manner the same is to be performed, we declare that what we claim isl. The combination of the annular va'lve A, the internal central valve,- B, for controlling the opening in valve A, the spindleOto valve B, spring S, acting on said valves, and .an adjustable pressure a power applied to said spindle, substantially as described.

2. The combination of the annular valve A, the internal central valve, B, for controlling the opening in valve A, the spindle C to valve B, a spring, S, acting on valve A, a collar, D, connecting with spindle O and serving as a bearing for spring S, and a nut, (Z, for regulating the pressure of said spring,substantially as described.

3. The combination, with a valve having an opening therein and a second valve for controlling said valve,of a Whistle adjacent to the opening in said first valve, to sound an alarm when said second valve is moved from its seat, substantially as described.

4. The combination of the annular valve A, the internal central valve, 13, for controlling the opening in said valve, and stops N and N, permitting the rotation of said valves, substantially as described.

In testimony whereof we have hereto set our hands this 17th day of October, 1884.

\V. NEXVZAM NICHOLSON. ARTHUR THOMAS ALLCOCK.

Witnesses:

W. E. HAMMOND, E. BOUSFIELD,

20th of Ncwarhon-T; c211. 

